This invention relates to high power amplifier arrangements which are suitable for the amplification of electrical signals having frequencies which extend over a wide band. It is often necessary to provide a greater output power than can be generated by a single amplifier device, and thus a number of such devices are used in combination so that together the total power handling requirement can be met.
One form of high power amplifier arrangement which is capable of operating over a wide frequency band is that known as a distributed amplifier. Such amplifiers are particularly suitable for use with vacuum valves, as they take advantage of the valve electrode capacitances which are arranged to form part of input and output delay lines. Distributed amplifiers are described in our earlier U.K. Pat. Nos. 846,633 and 2,040,635B.
A disadvantage which can arise with a distributed amplifier is that, if it operates into a mismatched load, the voltage which builds up on the output delay line can be unacceptably high, and thus to allow for this possibility it may be necessary to operate such an amplifier at well below its theoretically possible maximum rating. The present invention seeks to provide an improved higher power amplifier arrangement.